Antenna support enclosing slug-tuned inductor which is adjustable through a socket in which antenna is mounted



Aug. 2, 1966 A. c. NUTTLE 3,264,547

ANTENNA SUPPORT ENCLOSING SLUG-TUNED INDUCTOR WHICH IS ADJUSTABLETHROUGH A SOCKET IN WHICH ANTENNA IS MOUNTED Filed June 29, 1964flrzdrew 6. N 245170 United States Patent 3,264,647 ANTENNA SUPPORTENCLUSING SLUG-TUNED INDUCTOR WHHJH IS ADJUSTABLE THRQUGH A SOCKET INWHICH ANTENNA 1S MOUNTED Andrew C. Nuttle, Gain Electronics, Inc., 138Lincoln St., Manchester, NH. Filed June 29, 1964, Ser. No. 378,787 11Claims. ((Il. 343-745) The field of the present invention is that ofantenna mounts and couplers or tuners and the invention relates moreparticularly to a combined mount and tuner of especially compact andefiicient arrangement.

Objects of the invention are to provide an antenna mount whichintegrally incorporates an adjustable antenna coupler, so thatelectromagnetic wave energy .can be efficiently coupled to the antennaand so that the resonant characteristics of the antenna can be easilyadjusted to complement the characteristics of the environment in whichit is to be used. Further objects are to provide a combination antennamount and tuner which can be easily installed especially on cars orother conveyances, which presents a functionally attractive appearance,which is mechanically rugged, which exhibits stable electriccharacteristics, regardless of weather, wear and vibration; theelectrical characteristics of which can be quickly and easily adjustedwith a minimum of tools and with the antenna in place; in which theelectrical components are protected from the elements for exterior, suchas automotive, use; which is of relatively simple and inexpensiveconstruction and which is of compact and unobtrusive appearance.

The substance of the invention may be characterized as contemplating theincorporation of an antenna tuner into an antenna mount whilemaintaining a very compact and uncluttered construction and appearanceby employing a single aperture into the mount for both receiving theantenna rod and for providing access to the tuning adjustment. In thepreferred embodiment the tuning adjustment is obtained by adjustablypositioning a tuning slug relative to a coil. The slug is mounted on athreaded spindle extending into the same aperture which receives theantenna rod. Preferably there are means for coupling rotational motionof the rod to the spindle so that tuning adjustments may be made byrotating the antenna rod.

In one particular aspect the invention contemplates an antenna tuningmount involving a coaxial connector and a hollow cylindrical coil formattached to the connector coaxially therewith. A coil is wound aroundthe form and a rigid conforming envelope of insulating material supportsthe connector, the coil form and a coaxial sleeve is alignedrelationship. A tuning slug fits within the form and a threaded spindleis provided for mounting the slug on the sleeve for movement axially ofsaid coil.

These and other objects and novel characteristics of the invention willappear from the following description of a preferred embodiment thereofby way of example.

The description refers to a drawing in which:

FIG. 1 is a side view of a complete antenna mount and tuner;

FIG. 2 is an exploded view, partially in section, of components of themount;

"ice

FIG. 3 is a vertical sectional view of the mount taken on the line 3-3of FIG. 5;

FIG. 4 is a schematic circuit diagram of the tuner; and

FIG. 5 is a diagram in plan, for the purpose of showing the section line33.

The mount includes a conventional coaxial connection 12 which involvesan outer, internally threaded barrel 1-4 and a center pin 16 which ismounted coaxially therewith on an insulating disc 17. On top of thisconnector is placed an insulating plastic coil form 20. This coil formincludes a broad annular groove 22 for a coil 32, and longitudinal slots24 for the leads to the coil. These slots are filled with plastic afterwiring and assembly, as subsequently explained, and that slot whichwould be cut through by the section plane at the right side of FIG. 3 isso shown, filled up.

A metallic cap element 26 having a skirt portion 27, fits snugly overthe upper end of the coil form 20 and an extension element 28, alsometallic, is coaxially mounted at the closed end of the cap element 26by means of matching threads. It will be convenient to refer to the twoelements 26 and 28 as a sleeve; this sleeve has two parts mainly becauseit has considerably different diameters and can be more conveniently andeconomically so manufactured in two parts. The central bore of the upperpart 28 of the sleeve is internally threaded to receive thescrew-threaded mounting spindle 29 of a brass or powdered iron tuningslug 30. The parts are so dimensioned that when the sleeve is placedover the coil form 20, the tuning slug 30 is disposed within the centralbore 21 of the coil form 20. The lower end of antenna rod 50 extendsinto central bore of part 28, coaxially with the screw 29.

According to the presently preferred practice of the invention, anantenna tuning coil 32 is wound in the annular groove 22 and isconnected with fixed ceramic capacitors 34 and 36 so as to be resonantin the band of frequencies in which the antenna is to be used. Theconnections are conventional and the circuit employed for this purposeis shown in FIG 4. Appropriate leads from the coil 32 are brought outthrough the longitudinal slots 24 and the capacitors 34 and 36 aresoldered to one of these leads. Capacitor 36 is soldered to the barrel14 at 27, FIG. 2, and capacitor 34 is soldered to a lead 35 which asindicated in FIG. 3 extends to the central pin 16. The connection of thecoil to the antenna proper is made by means of a screw 38 threaded intothe skirt portion 27 of the cap element 26 as shown in FIG. 3.

After the circuit is wired and the sleeve 26, 28 assembled with the coilform 20, an encapsulating envelope and base 40 of an insulating plasticis molded around the connector 12, the coil form 20, the capacitors 34and 36 and the lower portion of the sleeve. The plastic flows into theannular groove 22 and around the coil 32 through the longitudinal slots24, but is kept from filling the central bore 21 of the coil form 20 bythe tight fit of the skirt 27 around the coil form at its upper end.

It will be understood that the inside threaded barrel 14 is screwed to aconventional fitting and that the base 40 will contact a supportingsurface. The mode of fastening the present mount to a support is notpart of the present invention and can be accomplished in a suitablemanner.

The sleeve includes at its upper end means for mounting an antenna rod.The upper end of the sleeve is threaded at 42 and includes a conicalrecess 44 (FIG. 2) opening into its central bore. A nut 46, similar to agland nut, fits over these threads and contains a deformable ferrule 48.The lower end of an antenna rod 50, inserted into the sleeve through thenut 46 and the ferrule 48, can be rigidly held in position by tighteningthe nut 46thereby clamping the ferrule 48 tightly around the rod andsecurely holding it in position. This clamping action also provides anexcellent seal against dirt and the effects of the elements.

Preferably the lower end of the antenna rod 50 is provided with ablade-like extension 52 and the upper end of the tuning slug spindle 29is provided with a corresponding screw-head slot 54 so that the antennarod 50 and the spindle 29 can be engaged for transmitting rotationalmotion. In this way the axial position of the tuning slug 30 and hencethe inductance of the coil 32 can be easily adjusted by rotation of theantenna itself so that the effective resonant frequency of the antennaand tuner can be adjusted over a useful band of frequencies and so thatcompensation can be made for the characteristics of the antenna inrelation to the environment in which it is to be operated.

Situations may exist when it is more convenient to remove the antennafrom the mount, turn the threaded spindle 29 with a screwdriver insertedin place of the antenna, and remount the antenna. Also, even thoughsubsequent adjustments can be made by rotating the antenna while it isin the mount, preliminary adjustment may be made by a screwdriver beforethe antenna is mounted.

In all of these situations, whether the screw is turned by the antennaor by a separate tool, access for adjust ment of the slug is provided bythe axial bore which is adapted to receive the antenna. Thus, provisionof an additional opening into the mount for adjustment of the slug isrendered unnecessary.

The slot 54 in the top of the screw is only one example of a shaping ofthe top so that it can be engaged to rotate the screw. Thus the top ofthe screw might carry an upstanding blade, and either the antenna rod ora tool might have a corresponding slot. The general thought as to theupper end of the screw is that it shall have preferably small lengthwiseextending areas non-concentric with the screw axis, so that it can beengaged and rotated. In the preferred form shown these areas are theside walls of the slot 54.

As can be seen from FIG. 1, the complete mount is quite compact andexhibits a smooth and pleasing appearance. The simple internalarrangement provides stability of electrical characteristics, and, sinceonly one, tightly sealed aperture is necessary, the electricalcomponents are well protected.

While a particular embodiment has been shown by way of illustration itshould be understood that the invention includes all modifications andequivalents falling within the scope of the appended claims.

I claim:

1. An antenna tuning mount comprising:

a sleeve having a bore to receive an antenna rod;

means for securing the rod in said bore;

a variable inductance coil in the mount in circuit with the sleeve;

a tuning slug; and

a screw for moving the slug axially of the coil, said screw beingcoaxial with said bore with the head of the screw accessibletherethrough.

2. An antenna tuning mount according to claim 1 in which the screw hasat its upper end lengthwise extending areas non-concentric with thescrew axis and adapted for engagement to turn the screw.

3. An antenna tuning mount according to claim 1 ineluding,

an envelope of insulating plastic surrounding the lower part of thesleeve and extending within the sleeve around the coil.

4. Antenna tuning mount according to claim 1 including,

a capacitor in circuit with the inductance coil; and

an envelope of insulating plastic surrounding the lower part of thesleeve, the coil and the capacitor.

5. An antenna tuning mount comprising:

a hollow cylindrical coil form;

a coil wound around said form;

means for connecting one end of said coil to radio frequency energy;

a tuning slug fitting within said form;

a screw means for mounting said slug relative to said form for movementaxially of said coil;

an insulating envelope enclosing said coil and form;

and

mean-s for releasably mounting an antenna rod coaxially with said screwmeans whereby access for the adjustment of said slug can be obtainedthrough the antenna mounting means.

6. An antenna tuning mount according to claim 5, further comprisingmeans for coupling rotational motion of said antenna rod to said screwmeans for adjustment of said slug.

7. An antenna tuning mount comprising:

a hollow cylindrical coil form;

a coil wound around said form;

means for connecting one end of said coil to radio frequency energy;

a tuning slug fitting within said form;

a hollow sleeve coaxial with said form;

screw means mounting said slug on said sleeve movement axially of saidcoil;

an insulating envelope surrounding said form, said coil and the end ofsaid sleeve nearest said slug; and means for releasably mounting anantenna rod in the other end of said sleeve;

said screw means being accessible through the sleeve upon removal ofsaid antenna rod.

8. An antenna tuning mount comprising:

a hollow cylindrical coil form;

a metallic sleeve including a portion fitting around a portion of saidcoil form;

a coil wound around said coil form and connected at one end to saidsleeve;

means for connecting the other end of said coil to radio frequencyenergy; a tuning slug fitting within said form;

screw means mounting said slug on said sleeve for movement axially ofsaid coil;

means for releasably mounting an antenna rod coaxially on said sleeve;and

means for coupling rotational movement of said antenna rod to said screwmeans for adjustment of said slug.

9. An antenna tuning mount comprising:

a coaxial connector;

a helical coil coaxial with said connector;

a tuning slug for said coil;

screw means for mounting said slug which permits adjustment of the slugaxially of the coil;

an antenna rod;

means for coupling rotational movements of said rod to said screw means;and

means for releasably clamping said antenna rod coaxially with said coil.10. An antenna tuning mount according to claim 9 including an externallyrounded, rigid, conforming envelope of insulating material enclosingsaid connector and said coil.

11. An antenna tuning mount comprising:

a coaxial connector;

for

a hollow cylindrical coil form attached to said connector coaxiallytherewith;

a coil wound around said form;

an elongate sleeve coaxial with said form;

a rigid conforming envelope of insulating material surrounding saidconnector, said coil form and the lower part of said sleeve;

a tuning slug fitting within said form;

screw means for mounting said slug on said sleeve for movement axiallyof said coil;

6 an antenna rod; means for coupling rotational movement of said rod tosaid screw means; and means for releasably clamping the antenna rodwithin said sleeve.

No references cited.

HERMAN KARL SAALBACH, Primary Examiner.

M. NUSSBAUM, Assistant Examiner.

1. AN ANTENNA TUNING MOUNT COMPRISING: A SLEEVE HAVING A BORE TO RECEIVEAN ANTENNA ROD; MEANS FOR SECURING THE ROD IN SAID BORE; A VARIABLEINDUCTANCE COIL IN THE MOUNT IN CIRCUIT WITH THE SLEEVE; A TUNING SLUG;AND A SCREW FOR MOVING THE SLUG AXIALLY OF THE COIL, SAID SCREW BEINGCOAXIAL WITH SAID BORE WITH THE HEAD OF THE SCREW ACCESSIBLETHERETHROUGH.